1. Field of the Invention
The invention relates to a farm machine having a body equipped with work elements, and a tow-bar comprising a primary tow-bar designed to be connected to a tractor vehicle, a secondary tow-bar connected to the body of the machine and a connecting and transmission device linking the primary tow-bar to the secondary tow-bar and by which the work elements are driven from the power take-off of the tractor vehicle.
2. Discussion of the Background
Farm machines, in the form of a mower-conditioner having a primary tow-bar, a secondary tow-bar and a connecting and transmission device as mentioned above, are known, as disclosed in EP 0 027 295 A1. The primary tow-bar of this known farm machine is formed by a curved member and is designed to be connected to the two lower bars of the hitching device of a tractor vehicle to which the farm machine must be hitched. The primary tow-bar can thus pivot around a first axis formed by the two connecting points to the lower bars. This first axis extends, in a normal displacement position, at least approximately horizontally and at least approximately at a right angle to the direction of advance.
The connecting and transmission device comprises two parts that can pivot in relation to one another around a second axis directed upwardly (in the normal displacement position, this second axis extends at least approximately vertically). In this known farm machine, the primary part of the connecting and transmission device consists of a primary angle transmission housing that includes a barrel directed upwardly and guided for rotation in a hub welded to the front end of the secondary tow-bar, which constitutes the secondary part of the connecting and transmission device. The merged longitudinal axes of the barrel and the hub define the second axis. The primary angle transmission housing supports an input shaft whose axis of rotation extends in the direction of advance, as well as an output shaft guided in rotation in the barrel and whose axis of rotation is merged with the second axis. Inside the primary angle transmission housing, these two shafts are coupled by means of a pair of bevel gears. Outside the primary angle transmission housing, the input shaft is coupled to a telescopic shaft with universal joints by which it is drivingly connected to the power take-off of the tractor vehicle. The output shaft is equipped at its upper end with a pulley transmitting the movement to the work elements by means of belts.
In another embodiment described in document EP 0 027 295 A1, the secondary part of the connecting and transmission device also consists of an angle transmission housing. This secondary angle transmission housing exhibits a hub directed downwardly, in which the barrel of the primary angle transmission housing is guided in rotation. The output shaft of the primary angle transmission housing enters inside the secondary angle transmission housing and is coupled there by means of a pair of bevel gears to the output shaft of said secondary angle transmission housing. The latter output shaft transmits the movement to the work elements.
The primary tow-bar is connected to the primary part of the connecting and transmission device by a pivot connection provided at the middle part of the curved member, with an axis directed at least approximately in the direction of advance. In fact, the curved member is mounted on the input shaft of the primary angle transmission housing so as to be able to pivot around the axis of rotation of the input shaft.
While in the embodiment described in EP 0 027 295 A1, the curved member forming the primary tow-bar is mounted directly on the input shaft of the primary angle transmission housing, an embodiment has also been marketed in which the curved member is mounted on a pivot pin attached to the primary angle transmission housing and which extends parallel to the input shaft and underneath the latter. The curved member is thus also able to pivot around an axis directed at least approximately in the direction of advance.
As a result of the three axes discussed above, the farm machine can perfectly adapt to the contour of the ground independent of the position of the tractor vehicle to which it is hitched, and will enjoy great maneuverability both during work and in transport. Moreover, during work, this great independence of the farm machine in relation to the tractor vehicle does not have an effect on the various elements designed to transmit the movement to the work elements. However, in these various known embodiments, the curved member forming the primary tow-bar is mounted in an overhanging manner on the primary angle transmission housing and more generally on the connecting and transmission device. This is detrimental to the life of the connecting and transmission device, the danger furthermore increasing with the increase in the work widths and in correspondence with the weight of the farm machines.